Various wind power tower designs made of prefabricated segments have become known in the state of the art. In these towers, the lowest tower segment and lowest tower section are connected in a stable manner with a separately made foundation so the occurring forces can be induced there. Thus, great importance is attached to the connection of the tower or lowest tower segment to the foundation. Therefore, when the foundation is made in in-situ concrete, the corresponding fastening devices for the wind power tower must be provided. For example, in wind power towers made of steel segments, it is known that an anchor cage with numerous threaded rods is embedded in the concrete foundation, on which later the tower's foot section with its fastening bore holes will be fastened. The anchor cage is prefabricated and matches the fastening points of the foot section.
For such a steel tower, DE 20 2009 013 844 U1 merely suggests casting in jacket pipes for individual tie bolts instead of the anchor cage. The positioning of the individual jacket pipes for the tie bolts takes place, in turn, with such an anchor cage. However, when tendons such as tensioning strands, tensioning wires or tensioning chords are used, a very exact orientation of the jacket pipes is necessary.
DE 101 26 912 A1 describes a wind power tower made of pre-stressed concrete, which is pre-stressed outside the tower's wall with tendons running between a top bearing and a foundation. The difficult adjustment of empty pipes in the formworks for the tower's wall described there can thus be dispensed with. This patent says nothing about the installation and orientation of jacket pipes in the foundation.
In practice, there are often problems when tendons are guided in tensioning channels. For example, if the axis deviates a little bit between the tendon and tensioning channel, there can already be bending during the guiding, and this damages the tendons. This occurs, for example, in transitional spots between two adjoining tensioning channel sections or between a freely tensed tendon section and one running in a tensioning channel. For this reason, the jacket pipes or tensioning channels are usually provided with funnel-shaped expansions in one end to reduce such bending. DE 201 22 941 U1 shows segments of a wind power tower whose tensioning channels are executed accordingly. The WO 00/14357 A2 also shows tensioning channels and jacket pipes with a funnel-shaped expansion in a tensioning channel.